1. Field of the Invention
The present invention relates to a self-grounding soldering iron tip, and more particularly, to a replaceable soldering tip arrangement with improved tip-to-ground continuity as well as a means for retaining the tip in the soldering iron to a soldering iron for use therewith.
2. Description of the Related Art
In one traditional soldering iron and soldering tip arrangement, the soldering tip is removably secured by means of a laterally threaded set screw. The screw digs into the tip, maintaining ground between the tip and the barrel of the soldering apparatus. In another traditional soldering iron and soldering tip arrangement, such as that found in WELLER(copyright) Brand products (COOPER INDUSTRIES INC.), including the WTCP and EC Series of Soldering Stations, tip retention and ground continuity is achieved through the use of a draw bar and nut arrangement in which the soldering tip fits onto a heater and a drawbar fits over the tip and is fastened to the soldering iron heater with a nut. In this arrangement, tip grounding is maintained via the contact between the draw bar flange and a shoulder on the tip, and/or the back or internal portions of the tip contacting grounded metal members of the soldering iron heater. Also known is the use of a grounded hardened steel spike which digs into the back end of the tip as it is tightened down with a draw bar; see, the UNICON 107 Model Soldering Station by Japan Unix Co., Ltd of Japan. A significant problem with such arrangements is the failure of ground which occurs with use. Also, set screws can become worn, making replacement necessary. Still further, it is not possible to simply plug in and begin use of the soldering iron due to the need to perform at least one fastening operation, such as tightening of a set screw or tightening down of a draw bar, etc.
When all of the components get hot during use, oxides build up and the ground at the tip is lost, requiring a thorough cleaning of the heater and replacement of the tip. Moreover, the ground connection is located in the vicinity of the heat source and oxidation occurs more rapidly in this heated area. Another problem with the prior art arrangements is flux/solvent fume contamination. Often, the tip and setting screws or holding means are made of incompatible materials which also cause a reaction due to the dissimilarity or incompatibility of the metals.
Maintaining ground at the tip is important to help prevent the soldering iron from causing EOS/ESD damage to sensitive electronic assemblies. At present, the relevant specifications require resistance between the tip and ground to be no greater than 5 ohms. Moreover, ANSI-JSTD-001 guidelines for soldering irons require that ground is maintained.
Hence, there is a need for a removable soldering tip which provides retention of the tip and a positive, reliable ground connection which is less susceptible to failure due to oxidation, contamination or corrosion. Likewise, it is desirable to achieve these benefits without having to perform a tightening or fastening operation each time a tip is attached to the soldering iron.
Accordingly, it is a primary object of the present invention to provide an easily removable, but securely attached soldering tip which provides improved electrical contact between the tip and the apparatus.
Another object of the present invention is to provide a soldering tip arrangement in which the ground connection is located remote from the heat source, solder flux fumes and other contamination to slow down the rate of oxidation.
Still another object of the present invention is to provide a soldering tip arrangement in which the ground contact surfaces are wiped clean each time plug-in or plug-out of the tip occurs.
It is also an object of the present invention to provide a soldering tip arrangement wherein the ground contact surfaces are made of the same or compatible materials, so as to avoid reactions that occur between dissimilar incompatible metals.
In accomplishing these and other objectives of the invention, there is provided a self-grounding soldering tip arrangement having a soldering tip and a heater bobbin for receiving the soldering tip. A bobbin tube extends within the heater bobbin, and spring means removably retain the soldering tip within the bobbin. The spring means has a first end connectable with the soldering tip and a second end connectable with the bobbin tube. The connection between the spring means and bobbin tube provides tip-to-ground continuity.
The spring means and bobbin tube are made of the same or compatible materials and hence avoid any reactions that occur between dissimilar or incompatible metals. Moreover, the spring and bobbin tube ground connection is located in a relatively cool location remote from the heat source to slow down oxidation.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.